asp.net 中的后台工作者（线程池）

Question

我有一个 asp.net 网络表单，它将大约 25-30 个项目（当用户从​​表单发出后续请求时需要信息）写入自定义缓存。目前所有这些都在主线程上同步发生。但是在更高的负载下，addcache 正在成为一个瓶颈。

如何在后台运行此任务而不消耗 asp.net 工作进程线程池中的线程。

Answer 1

替代方案：

完全异步：

• 从客户端使用AJAX调用服务端代码，并添加代码监控调用过程

  我刚刚添加了一个与此过程相关的答案：

  https://stackoverflow.com/a/11524718/1268570

部分异步：

从客户端到服务器的调用将是同步的，这意味着在整个过程结束之前不会将响应返回给客户端，但真正的代码将异步执行，释放 ASP.Net 使用的线程，从而提高可伸缩性

• 异步执行页面。您需要在后面的 ASPX 代码中实现 IHttpAsyncHandler 接口。这是一个例子：

      public partial class _Default : System.Web.UI.Page, IHttpAsyncHandler
      {
          public void EndProcessRequest(IAsyncResult result)
          {
              var context = (result as AsyncOperation).Context;
  
              context.Response.Write(string.Format("<p>End Process Request on {0}</p>", Thread.CurrentThread.ManagedThreadId.ToString()));
          }
  
          public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData)
          {
              var operation = new AsyncOperation(cb, this.Context, extraData);
              operation.StartAsync();
  
              this.Context.Response.Write(string.Format("<p>Begin Process Request on: {0}...</p>", Thread.CurrentThread.ManagedThreadId.ToString()));
  
              return operation;
          }
      }
  
      public class AsyncOperation : IAsyncResult
      {
          private AsyncCallback asyncCallback;
  
          public AsyncOperation(AsyncCallback asyncCallback, HttpContext context, object state)
          {
              this.AsyncState = state;
              this.asyncCallback = asyncCallback;
              this.Context = context;
  
              this.IsCompleted = false;
              this.AsyncWaitHandle = null;
              this.CompletedSynchronously = false;
          }
  
          public HttpContext Context { get; private set; }
          public object AsyncState { get; private set; }
          public WaitHandle AsyncWaitHandle { get; private set; }
          public bool CompletedSynchronously { get; private set; }
          public bool IsCompleted { get; private set; }
  
          public void StartAsync()
          {
              ThreadPool.QueueUserWorkItem(new WaitCallback(StartAsyncOperation), this.AsyncState);
          }
  
          public void StartAsyncOperation(object workItemState)
          {
              // place here the async logic
  
              this.Context.Response.Write(string.Format("<p>Long Async operation started on: {0}</p>", Thread.CurrentThread.ManagedThreadId.ToString()));
              Thread.Sleep(2000);
              this.Context.Response.Write(string.Format("<p>Long Async operation ended on: {0}</p>", Thread.CurrentThread.ManagedThreadId.ToString()));
              this.IsCompleted = true;
              this.asyncCallback(this);
          }
      }
  

  输出

• 创建一个 HttpAsyncHandler。您需要创建一个自定义的HttpHandler 实现IHttpAsyncHandler 接口。示例：

  public class AsyncHandler : IHttpAsyncHandler
  {
      public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData)
      {
          var operation = new AsyncOperation(cb, context, extraData);
          operation.StartAsync();
  
          context.Response.Write(string.Format("<p>Begin Process Request on: {0}...</p>", Thread.CurrentThread.ManagedThreadId.ToString()));
  
          return operation;
      }
  
      public void EndProcessRequest(IAsyncResult result)
      {
          var context = (result as AsyncOperation).Context;
  
          context.Response.Write(string.Format("<p>End Process Request on {0}</p>", Thread.CurrentThread.ManagedThreadId.ToString()));
      }
  
      public bool IsReusable
      {
          get { return false; }
      }
  
      public void ProcessRequest(HttpContext context)
      {
          throw new NotImplementedException();
      }
  }